Computer systems commonly provide a software power-down feature (“soft power-down”). Any data that may be stored in a volatile memory can be corrupted or lost if the power supplied to a computer is abruptly terminated (a “hard power-down”). The soft power-down feature prevents data stored in a non-volatile memory from being lost or corrupted by closing programs and files in an orderly manner, and terminating the power supplied to the computer system's circuits only after all of the data has been saved. The soft power-down feature is commonly invoked by issuing a command to the operating system. For example, the soft power-down command can be issued by selecting a “Turn Off Computer” option from a menu. Depending on the particular computer system, the soft power-down usually takes a minute or two to complete.
An uninterruptible power supply (“UPS”) is commonly used in those computer systems in which it is critical to avoid corruption or loss of data due to an unanticipated hard power-down. The UPS is connected in series between a primary power source, such as a wall outlet, and the computer system. The UPS includes circuitry for monitoring the primary power source. The UPS immediately switches the load to a backup power source when it senses that the primary power source has failed. Typically, the backup power source is a battery that is capable of supplying power to the load for a limited period of time. A UPS generally includes a microprocessor or a logic circuit that causes the UPS to send a power-down signal to notify the operating system that the UPS is furnishing power from the backup power source. In response to the power-down signal, the computer system causes the operating system to execute a soft power-down. After a predetermined time period (that is longer than the maximum time required for the operating system to complete the soft power-down), the UPS stops furnishing power from the backup power source. The UPS typically supplies power for about 3 minutes after switching to the backup power source.
Power monitoring and protection software (“UPS Control Software”) is available to work with a UPS. One such UPS Control Software program marketed as POWERCHUTE PLUS is available from American Power Conversion Corporation, West Kingston, R.I. and is apparently intended for use by a system administrator managing a number of distributed computer systems. An administrative computer running the UPS Control Software is coupled to the UPS. The UPS Control Software may include notification of impending shut down, power event logging, auto-restart upon power return, and battery conservation features. In addition, the UPS Control Software may provide automatic battery testing, power problem diagnosis, and may support the remote scheduling of shut downs and re-boots. Problems with the UPS Control Software include that the software provides many more functions than are needed for a simple application and that a second computer system is required to run the software. Thus, the use of the UPS Control Software to control a UPS may be unnecessarily complicated and expensive, especially if all that is needed is a means to prevent a hard power-down.
It is generally recognized that computer operating systems can be difficult to operate and require specialized knowledge or training. Moreover, as new versions of an operating system become available, there is a need for on-going training as the command or technique for performing a specific function frequently changes from one version to the next. For this reason, a user interface that hides the operating system from the user is often employed in special purpose computer systems as opposed to general purpose computer systems, such as a personal computer. A special purpose computer system that is designed to perform a single function or a limited set of functions will generally have software running on it that provides a simplified user interface. One example of a special purpose computer system is a portrait printing system. The portrait printing system employs a simplified user interface that permits editing and printing of images, but hides the operating system from the user. A problem with some special purpose computer systems is that the user interface does not provide for a soft power-down. Another problem with some special purpose computer systems is that the system may be enclosed in a cabinet making the computer's on/off switch inaccessible so that there may be no convenient way to power-up the system.
Accordingly, there is a need for a hardware switching apparatus for initiating a soft power-down and a remote power-up in a computer system that has as its power supply a UPS.